Supramolecular Structuring of Hydrogels and Transient Polymer Networks

该提案概述了合成两亲性聚合物的结构和行为的实验和理论研究。该研究计划要求设计、合成和表征大分子结构，其中包含采用明确定义的二级结构的低聚片段。这些折叠的片段暴露出信息丰富的表面，可以自组织成高阶形式。提出了五种不同类型的两亲性聚合物结构。其中三种将涉及序列特异性的苯乙烯低聚物，或作为接枝或端基连接到水溶性聚合物上，或与亲水性共聚物一起延伸链以产生多块主链结构。另外两种含有构象受限的苯乙炔大环片段，它们要么作为垂基团接枝到亲水聚合物上，要么连接到水溶性链的末端。含有大环片段的结构倾向于由平面环之间的面对面疏水结合而形成的纳米管状组织。与大环体系相反，包含寡聚片段的体系结构可以存在于构象有序或无序状态。因此，应该有可能设计出响应外部刺激而折叠或展开的序列。这可能导致瞬态网络和凝胶以规定的方式可逆地组装或拆卸。这项研究是为了更好地了解两亲性大分子的结构和性质。两亲性聚合物用于许多商业应用（例如，洗涤剂和水性涂料），它们在各种医疗应用和作为刺激响应材料中显示出相当大的前景。从基本观点来看，认为蛋白质也是两亲性大分子是很有趣的。考虑到蛋白质分子的多种功能，用合成物质模拟它们的行为是值得努力的。* * *

9808433 Moore The proposal outlines an experimental and theoretical study on the structure and behavior of synthetic amphiphilic polymers. The research plan calls for the design, synthesis, and characterization of macromolecular architectures containing oligomeric segments that adopt a well-defined secondary structure. These folded segments expose information-rich surfaces that can self-organize into higher-order forms. Five different types of amphiphilic polymer architectures are proposed. Three of these will involve sequence-specific phenylene ethynylene oligomers, either attached as grafts or end- groups to water-soluble polymers, or, chain-extended with a hydrophilic comonomer to produce a multiblock main-chain architecture. Two others contain conformationally restricted phenylacetylene macrocyclic segments, which will either be grafted as pendant groups onto a hydrophilic polymer or attached to the ends of a water-soluble chain. The architectures containing macrocyclic segments are predisposed toward nano- tubular organizations that result from face-to-face hydrophobic association between planar rings. In contrast to the macrocyclic systems, architectures that incorporate oligomeric segments can exist in either conformationally ordered or disordered states. Thus it should be possible to design sequences that fold or unfold in response to an external stimulus. This may lead to transient networks and gels that reversibly assemble or disassemble in a prescribed fashion. %%% The proposed research is being performed to better understand the structure and properties of amphiphilic macromolecules. Amphiphilic polymers are used in many commercial applications (e.g., detergents and waterborne coatings), and they show considerable promise in a variety of medical applications and as stimuli-responsive materials. From a fundamental standpoint, it is interesting to consider that proteins too, are amphiphilic macromolecules. Given the versatile functions perf ormaed by protein molecules, it is a worthwhile endeavor to mimic their behavior with synthetic substances. ***